The first trailer for theBrad Pittstarring film, (very loosely) based on the book by Max Brooks and directed by Marc Forster is here, but is it the Jason Bourne meets “The Walking Dead” vibe the director and studio were hoping for? Well, it’s certainly fast moving and aiming for an epic scope, even if the zombies remain somewhat undefined as a mass of moving CGI.

These zombies are obviously a lot more feral than the slow, plodding ones you usually see on screen, though still different from the “infected” in Danny Boyle‘s “28 Days Later” series. “They are like predatory animals that can’t control themselves,” Visual effects supervisor John Nelson (“Iron Man“) told EW about the undead on this film. Evidently the victims-turned-zombies in this film hew closer to a sci-fi-like transformation rather than supernatural resurrection. “I worked with tigers [while shooting “Gladiator“], and if you watch them when a horse goes by they go batty, even if they know they can’t reach it. When Zs see humans they do same thing, they activate. They launch themselves.”